This is my solution on how to work out the kinks for your audio to work in
Pinnacle Studio 10 on a Windows Vista PC.
Step 1- Open up Studio 10
Step 2- On top of your screen hit Setup>Capture Source, your settings should look like this.
Step 3- Change your Audio from whatever your normal setting was an put it on the line in setting.
Step 4- Change it back to what it was on in Step 2.
Step 5- go up to Setup>Video and Audio Preferences and Put your settings like shown and you should be able to record with sound now.
I am using my Internal Happauge Capture Card that came on my new computer and the sound never worked. There must be a bug which lets it work when you switch from one audio back to the original. Let me know if this helped you out
Thanks! XxHondaRid3rxX